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Re: RFC reminder: an alternative -fsched-pressure implementation


On 04/10/2012 09:35 AM, Richard Sandiford wrote:
Hi Vlad,

Back in Decemember, when we were still very much in stage 3, I sent
an RFC about an alternative implementation of -fsched-pressure.
Just wanted to send a reminder now that we're in the proper stage:

http://gcc.gnu.org/ml/gcc-patches/2011-12/msg01684.html

Ulrich has benchmarked it on ARM, S/390 and Power7 (thanks), and got
reasonable results.  (I mentioned bad Power 7 results in that message,
because of the way the VSX_REGS class is handled.  Ulrich's results
are without -mvsx though.)

The condition I orignally set myself was that this patch should only
go in if it becomes the default on at least one architecture,
specifically ARM.  Ulrich tells me that Linaro have now made it
the default for ARM in their GCC 4.7 release, so hopefully Ramana
would be OK with doing the same in upstream 4.8.
Sorry for forgetting about this and thanks for the remainder. I'll start looking at this patch thoroughly and reviewing it on this week (may be I'll do some benchmarks too).
I realise the whole thing is probably more complicated and ad-hoc
than you'd like.  Saying it can't go in is a perfectly acceptable
answer IMO.

The first impression I got for the patch when you submitted it, that it probably should go in.


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